2005 年 42 巻 3 号 p. 238-244
In order to examine the binding affinity of various estrogenic compounds to estrogen receptor β (ERβ), the cDNA encoding the hinge domain, the ligand-binding domain, and the C-terminal domain of quail ERβ was constructed and transfected into competent Escherichia coli. The binding assay performed using the supernatant of the cell lysates showed that bacterially-expressed ERβ has one single class of binding site for estradiol-17β with a dissociation constant of 4.90±0.16×10-9M. The competition studies indicated that the relative binding affinities for the synthetic estrogens, diethylstilbestrol and ethinyl estradiol, are very high, while those for the xenoestrogens, bisphenol A and nonylphenol, are very low. Coumestrol, known as one of phytoestrogens, can compete with estradiol-17β with higher binding affinity for ERβ than ERα.
